1. Field of the Disclosure
This specification relates to an inverter system for supplying direct current (abbreviated as “DC” hereinafter) electric power from a DC power supply source to a commercial alternating current (abbreviated as “AC” hereinafter) grid, and more particularly, a controller for a grid tied inverter system with an improved sequential control configuration (hereinafter, referred to as a control configuration) so as to immediately supply electric power required by the commercial AC grid.
2. Background of the Disclosure
A DC voltage which is generated by various DC energy supply sources such as photovoltaic energy, wind energy, fuel cells and the like for supply is inverted into an AC voltage, which is equal a grid voltage, by an inverter system so as to be supplied to grids.
The related art inverter system includes a DC-DC converter connected to an output of the DC energy supply source, and an inverter connected to an output of the DC-DC converter, to control an output current on the basis of a command value generated by a controller.
Also, the related art inverter system adjusts an input voltage command by applying a maximum power point tracking (can be abbreviated as “MPPT”) algorithm, so as to provide maximum electric power according to variation of grid loads.
In recent time, with the rise of the necessity to protect grids and limit a quantity of electric power generated and the establishment of related regulations, a technology of controlling electric power generated by the DC energy supply source below maximum electric power is required.
Since the controller of the related art inverter system outputs an inverter control signal using a DC link voltage, which is generated by outputting a control signal of the DC-DC converter, a plurality of control circuit sections are linked to one another to input and output signals, starting from an input voltage to an output current. Accordingly, the controller for the related art inverter system has a configuration that the plurality of control circuit sections have a unified configuration as one.
Therefore, to control electric power, required power should be found (or determined) through repetition of controlling an input voltage command, sequentially operating the plurality of control circuit sections, and finally providing an output current.
However, the related art control method has several problems of increasing a required processing time due to a complicated control configuration, and failing to immediately provide an output current corresponding to specific electric power due to a slow response time (or a low response speed).
Various prior technologies including Korean granted Patent No. 10-1032720 are searched for in relation to the grid tied inverter system, but there is not any technology associated with the technical task which is considered in the present invention.